1. Field of the Invention
The present invention relates to a rear holder for a waterproof connector.
2. Related Art
A waterproof connector is used for electric connection in various products such as motorcycles. A waterproof connector is roughly made up of a connector main body for connecting to a mating waterproof connector, and a rear holder for holding a wire connected to a terminal inserted into the connector on the terminal insertion side and for preventing water from entering from the terminal insertion side.
Japanese Utility Model Application No. 59-19747 (or Japanese Utility Model Laid Open No. 60-133587), also filed by the present applicant, discloses a rear holder .theta. shown in FIG. 5B (as seen from the mating housing). A rubber material member 52 is obtained by insert-molding a rubber forming material into a stopper frame 51 made of resin as shown in the perspective view of FIG. 5A. Reference numeral 53 indicates wire insertion holes.
FIG. 5C shows the rear holder .theta. taken along the line V--V of FIG. 5B. In FIG. 5D, the rear holder .theta. is attached to a connector main body 55, and a terminal 62 connected to a wire 61 is being inserted into one of the wire insertion holes 53.
The wire insertion hole 53 is made small for a waterproof purpose, and the terminal 62 is often tilted against the insertion direction when inserted into the wire insertion hole 53. At this point, the rubber material member 52 made of an elastic material does not have enough straightening ability. As can be seen from the figure, the edge of the terminal 62 is brought into contact with the wall end face of the connector receiving chamber 56 at the point indicated by the arrow, thus hindering terminal insertion.
With the rear holder .theta. disclosed in Japanese Utility Model Application No. 59-19747, there has been a problem that workability in terminal insertion is very low in automatic connector insertion.
To solve such problem, Japanese Patent Application Laid-Open No. 8-96883 discloses a rear holder as follows.
FIG. 6A shows the rear holder L as seen from the terminal insertion side. FIG. 6B is a side view of the rear holder L. FIG. 6C shows the rear holder L as seen from the mating connector. FIG. 7A is a sectional view taken along the line VI--VI of FIG. 6A, and FIG. 7B is a sectional view taken along the line VI'--VI' of FIG. 6C.
As the inlet portion 74 of a wire insertion hole 73 of the rear holder L is made of resin and capable of preventing and correcting terminal tilt caused at the time of terminal insertion, workability in terminal insertion is excellent. However, there is a problem with a metal mold used for forming the rubber material member 72 of the rear holder L.
FIG. 7C shows a resin material member 71 prior to the rubber material member 72 of the rear holder L as seen from the terminal insertion side.
Reference numeral 71c indicates connecting holes for supplying a raw material from a rubber material holder forming portion 71b, which forms a rubber material holder 72b at the time of forming the rubber material member 72, to a lip portion 72a of the rubber material member 72. After the formation of the rubber material member 72, a connecting portion 72c is formed, and the rubber material holder 72b and the lip portion 72a are connected so as to integrally form the rubber material member 72. The resin material member 71 is first formed and inserted into a cavity of a metal mold used for forming the rubber material member. A rubber forming material is then introduced from the side of the rubber material holder 72b. The rubber forming material is thus supplied to the lip portion 72a from a gate (not shown) through the connecting holes 71c formed in the resin material member 71.
However, since an inlet portion 74 of each wire insertion hole 73 is situated on the side of the rubber material holder 72b, and the edge of the flow of the rubber member forming material becomes solidified due to the heat generated during the detour to avoid the inlet portion 74. As a result, a short shot is caused. Many short shots are caused in forming a rubber member of a multipolar connector with a more complicated detour. If the inlet portion 74 has a rectangular shape instead of a circular shape, even more short shots are caused, resulting in a sharp decrease in production yield. The number of occurrences of such short shots can be reduced to some extent by increasing the number of gates of the rubber member forming metal mold. However, this often makes the metal mold structure more complicated, and increases the production costs of the metal mold.
For the metal mold to produce the rubber material member 72, it is necessary to contrive to form the portion surrounded by the two-dot chain line of FIG. 7C. To prevent burrs during the formation of the rubber material member 72, a rubber material member forming metal mold 80 needs to be provided with a protrusion 81 which is in contact with the end face on the terminal insertion side in the vicinity of the inlet portion 74 of the terminal insertion hole 73 and the rubber material member holder forming portion 71b (the portion in contact with such metal mold protrusion is indicated by the two-dot chain line in FIG. 7C). Providing the protrusion 81 to the metal mold 80 sharply increases the production costs, and is more time-consuming. This has been a big problem especially in manufacturing a multipolar connector rear holder.